Linux and Unix under the DD command Ultra detailed

The DD command is powerful, and for some of the lower-level issues, using the DD command can often be surprisingly effective. Use a more or DD to back up the bare devices. It is not recommended, however, that if you need to back up your Oracle bare devices, you can use Rman backups, or use a third-party software backup, and it is not easy to manage using DD.

It is recommended that you use DD for Physical disk operations when necessary, and that other commands, such as the tar backup cpio, are more convenient if you are using the file system.

In addition, block device files are best used when using DD for disk operations.

Description

The DD command reads the INFILE parameter or standard input, does the

Specified conversions, then copies the converted data to the outfile

parameter or standard output. The input and output block size can

Specified to take advantage of raw physical I/O. note:the term block

Refers to the quantity of data read or written by the DD command in one

Operation and is isn't necessarily the same size as a disk block.

If=file input filename standard input Accurate province

Of=file output file name, standard output accurate province

Ibs=n input block size, n bytes (default 512)

OBS=N output block size, n bytes (default 512)

Bs=n set the input output block size at the same time

Cbs=n Conversion Buffer Size

Files=n copy and convert n input files before interruption

Cross n input blocks before skip=n copy

Find n blocks from the output file before oseek=n a copy

Find n blocks from input file before iseek copy

Seek=n equal to Oseek

Cono=ascic converts EBCDIC code to ASCII

EBCDIC ascii->; EBCDIC

A slightly different image of IBM ASCII converting to EBCDIC code

Blolk converts the ASCII record of the new stack break to a fixed length

Unblock converts a fixed-length ASCII record to a new line interrupt record

LCase transform Word will be low

UCase transform Word will go to high situation

Swab Exchange per pair of bytes

Do not stop processing when noerrir error

Sync will fill each block into IBS

Input device: infile parameter designation or standard input

Implements the specified transformation and then copies the transformation data to the OUTFILE parameter designation or standard output.

Input blocks and output block sizes can be specified by themselves, but must be multiples of the disk physical block size.

1

Usually, you need only write access to the output file. However,

When the output of file is isn't on a direct-access device and your use

The SEEK flag, you also need read access to the file.

2

The DD command inserts new-line characters only when converting

With the CONV=ASCII or Conv=unblock flags set; It pads when

Converting with the Conv=ebcdic, CONV=IBM, or Conv=block flags

Set.